The Massachusetts Department of Public Health (MDPH) Bureau of Infectious Disease (BID) will evaluate the effectiveness of a novel public health delivered intervention, driven by use of surveillance data, to (re-)engage PLWHA identified as out-of-care. The proposed research project, the Massachusetts Retention, Engagement, and Adherence to Care for Health (MassREACH), could significantly improve care engagement and adherence to ART, thereby contributing to reduced incidence, individual and population level improvements in health outcomes, and reductions in health disparities. Specific Aims Aim 1: Establish data sharing partnerships to identify out-of-care Aim 2: Implement an engagement in care intervention Aim 3: Calculate the number and percentage of out-of-care PLWH engaged and retained in care, and who achieve viral suppression Aim 4: Describe the important components and feasibility of a health department-clinic collaboration to identify out- of-care PLWHA Aim 5: Measure the cost-effectiveness of the intervention arm in terms of improved health of re-engaged individuals and reduced forward transmission Aim 6: Describe reasons that explain care status misclassifications Aim 7: Measure viral suppression at the beginning and end of the study to estimate the potential impact of this intervention at the community level. The MDPH proposes MassREACH as a strategy to evaluate the effectiveness of a novel public health delivered intervention to (re-)engage PLWHA identified as out-of-care. The project will build upon the existing public health infrastructure for HIV and STD prevention and control, and will complement existing linkage and engagement activities through use of novel strategies and techniques.